Celebrating Excel Day 40000

Excel hasn't been around for 40,000 days, but Excel's date system starts at January 1, 1900 (day 1), and today is day 40,000. Not for Mac users though – its default date system starts at January 1, 1904 (day 0), so you won't hit this milestone for another four years.

The two dating systems are explained in the Microsoft Knowledgebase article: Description of the differences between the 1900 date system and the 1904 date system in Excel.

Switch to a Different Date System

Whether you're using Excel on a Windows machine or on a Mac, you can switch from the default date system. Follow these steps to switch to the 1904 Date System in Excel 2007:

  1. Click the Office Button, then click Excel Options
  2. Click the Advanced category
  3. Scroll down to the section titled, When calculating this workbook
  4. Add a check mark to Use 1904 date system.
  5. Click OK


Keyboard Shortcuts for Dates

If you use these shortcuts, you'll have more time available for celebrating the 40,000 day milestone.

  • Enter today's date: Ctrl + ;
  • Format a date as dd-mmm-yy: Ctrl + #


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5 Responses

  1. Brian says:

    holy crap, I thought I was the only one who was onto this….

  2. Drew says:

    We use excel dates on my company’s server side technology and we all noticed, happy 40000!

  3. Ron de Bruin says:

    Hi Debra

    >its default date system starts at January 1, 1904

    As far as i know it start January 2, 1904

    Greetings from the Netherlands

  4. InternJessica says:

    Holy Moly, EXCEL nerds unite!! I JUST noticed it, a few days late, and thought to myself, goodness, the date number has started with a 3 the entire time I’ve been using Excel, I’m sure its been years since it changed from 2 to 3 and now to 4. HAPPY 40000!!

  5. Ron, thanks for the correction, and I changed the first line about the 1904 date system.

    InternJessica, I’m pretty sure the Excel Day 40000 party lasts all week, so you’re not too late!

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